In fact, if you make a text file on Linux, it will often have no file extension at all by default. When you open a file on Linux or Mac OS X, the operating system doesn’t just rely on the file extension. RELATED: How to Change Your Default Applications on Ubuntu: 4 Ways Windows attempts to present this in a prettier interface, but you’re still just choosing which application should be associated with which file extension. To configure which applications open files, you have to associate them with different file extensions. RELATED: Beginner Geek: 7 Ways You Can Change Default Applications and File Associations in Windows You can have a file extension with a single character or even more than three characters. File extensions aren’t special - they’re just a few characters after a period in the file name.

The “file type” is stored in the file name itself. Windows has no idea what type of file this is, but it will open properly if you open it using a text editor. Attackers can abuse this behavior - and other exploits - to disguise files with fake file extensions.ĭouble-click the file afterward and Windows will display a list of programs you can use to open files. This is why Windows hides file extensions by default, so people won’t accidentally delete these file extensions. This is why Windows warns you when removing the file extension, saying “If you change a file name extension, the file may become unusable.” It won’t become unusable forever - you can make it “usable” again by readding the original file extension. file extension - renaming the file to “Example” with no file extension - and Windows won’t know what to do with the resulting file. Windows knows it’s a text file because of the. For example, you might have a text file named Example.txt. Windows ignores MIME types, relying only on file extensions. RELATED: How Hackers Can Disguise Malicious Programs With Fake File Extensions

Try to run it as a program and it won’t run. Open it in a text editor and you’ll see gibberish. For example, a PNG image needs to be opened with an image viewer that supports PNG files.

A “file type” is simply information associated with a file that tells the operating system and programs how to interpret these 1’s and 0’s. The file system associated a file like “Document.pdf” with a chunk of these 1’s and 0’s.

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